The present invention relates in general to fluid filters and the structures and methods of sealing seams and interfaces of such filters which might be a location for possible fluid leakage. More specifically, but not exclusively, the present invention relates to spin-on filters and the structures and methods of sealing the seam interface between the nutplate and the outer shell or housing.
Attaching the shell of a filter to a nutplate can be accomplished in a number of different ways. However, rolling the shell over the outer, upright wall of the nutplate is the preferred method based on current manufacturing practices. The seam that is created by rolling the shell or by compression forming the shell around the outer wall of the nutplate is referred to as a xe2x80x9crolled-seamxe2x80x9d. One disadvantage of the rolled seam is that fluid tends to leak at the seam between the shell and the nutplate. One conventional method of sealing a fluid filter with a rolled-seam is to use a gasket on top of the rolled-seam between the filter and the filter head. However, a seal like this requires a groove on the filter head in order to prevent the gasket from extruding away under internal pressure.
Most of the fluid filter heads designed and used for regular spin-on filters have flat sealing surfaces without a groove. Consequently, designing a filter with a rolled seam for a conventional filter head (without a groove) requires a more creative gasket and retainer configuration. This is especially challenging when redesigning a spin-on filter with a double lock seam into a fluid filter design with a rolled seam. Double lock seams typically prevent fluid leakage from the seam so that a gasket is only used to seal the interface between the surface of filter head and the filter. When converting a fluid filter design from a double lock seam to a roll seam design, the gasket must seal the roll seam so as to prevent leakage from the seam.
In one redesign approach, a gasket at its outside diameter is supported by the inside diameter of the seam. A conventional O-ring design with a gland could be used for this application. Half of the gland could be formed by the retainer sitting on the nutplate and the other half could be created by the nutplate to seam wall. In this design, the gasket has to provide both a face seal and a radial seal concurrently. To obtain the radial seal against the seam, the inside diameter of the seam has to be controlled very tightly. Unfortunately, since the seam is obtained by forming, this inside diameter dimension cannot be controlled tightly.
Accordingly, in order to make sure that a radial seal is in fact established, the corresponding design must be predicated on an excessive interference fit between the gasket and the seam wall. This excessive interference fit in the form of compression on the gasket would ensure that there is a radial seal and that a radial seal would be established for all extremes within the tolerance ranges of the component parts. The difficulty with this approach is that the excessive interference fit makes assembling the gasket to the fluid filter during the manufacturing and assembly stages very difficult.
While important strides have been made in this field, there is still room for improvements in the areas of fluid control and installation/removal of fluid filter assemblies.
A fluid filter for spin-on attachment to a mounting base according to one embodiment of the present invention includes a nutplate, an outer shell having a formed edge secured to the nutplate, and a retainer having an inclined portion. An elastomeric gasket rests on the inclined portion, and the gasket is positioned adjacent the formed edge. Axial compression of the gasket against the retainer pushes the gasket radially outwardly into sealing contact with the formed edge of the outer shell.
A filter assembly according to another embodiment includes a mounting base having a mounting surface and a fluid filter. The fluid filter includes a nutplate threadedly secured to the mounting base, an outer shell secured to the nutplate to form a seam, and a gasket. An inclined portion is constructed and arranged to urge the gasket to radially expand to seal the seam from compression by the mounting surface.
One object of the present invention is to provide an improved retainer and gasket assembly for a fluid filter.
Related objects and advantages of the present invention will be apparent from the following description.